linux-kernel - Re: [PATCH v5 3/6] lib/base64: rework encode/decode for speed and stricter validation

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Message-Id: <20251117094652.b04c6cf841d6426f70f23d22@linux-foundation.org>
Date: Mon, 17 Nov 2025 09:46:52 -0800
From: Andrew Morton <akpm@...ux-foundation.org>
To: Guan-Chun Wu <409411716@....tku.edu.tw>
Cc: David Laight <david.laight.linux@...il.com>,
 andriy.shevchenko@...el.com, axboe@...nel.dk, ceph-devel@...r.kernel.org,
 ebiggers@...nel.org, hch@....de, home7438072@...il.com, idryomov@...il.com,
 jaegeuk@...nel.org, kbusch@...nel.org, linux-fscrypt@...r.kernel.org,
 linux-kernel@...r.kernel.org, linux-nvme@...ts.infradead.org,
 sagi@...mberg.me, tytso@....edu, visitorckw@...il.com, xiubli@...hat.com
Subject: Re: [PATCH v5 3/6] lib/base64: rework encode/decode for speed and
 stricter validation

On Sun, 16 Nov 2025 18:28:49 +0800 Guan-Chun Wu <409411716@....tku.edu.tw> wrote:

> > Reviewed-by: David Laight <david.laight.linux@...il.com>
> > 
> > But see minor nit below.
> 
> Hi David,
> 
> Thanks for the review and for pointing this out.
> 
> Andrew, would it be possible for you to fold this small change 
> (removing the redundant casts) directly when updating the patch?
> If that’s not convenient, I can resend an updated version of the
> series instead. 

Sure, I added this:


--- a/lib/base64.c~lib-base64-rework-encode-decode-for-speed-and-stricter-validation-fix
+++ a/lib/base64.c
@@ -83,7 +83,7 @@ int base64_encode(const u8 *src, int src
 	const char *base64_table = base64_tables[variant];
 
 	while (srclen >= 3) {
-		ac = (u32)src[0] << 16 | (u32)src[1] << 8 | (u32)src[2];
+		ac = src[0] << 16 | src[1] << 8 | src[2];
 		*cp++ = base64_table[ac >> 18];
 		*cp++ = base64_table[(ac >> 12) & 0x3f];
 		*cp++ = base64_table[(ac >> 6) & 0x3f];
@@ -95,7 +95,7 @@ int base64_encode(const u8 *src, int src
 
 	switch (srclen) {
 	case 2:
-		ac = (u32)src[0] << 16 | (u32)src[1] << 8;
+		ac = src[0] << 16 | src[1] << 8;
 		*cp++ = base64_table[ac >> 18];
 		*cp++ = base64_table[(ac >> 12) & 0x3f];
 		*cp++ = base64_table[(ac >> 6) & 0x3f];
@@ -103,7 +103,7 @@ int base64_encode(const u8 *src, int src
 			*cp++ = '=';
 		break;
 	case 1:
-		ac = (u32)src[0] << 16;
+		ac = src[0] << 16;
 		*cp++ = base64_table[ac >> 18];
 		*cp++ = base64_table[(ac >> 12) & 0x3f];
 		if (padding) {
_